1. Field of the Invention
The present invention relates to an image surveillance/retrieval system which surveils an image inputted from a surveillance camera on a predetermined condition, and which retrieves an image recorded therein according to a predetermined query.
2. Description of Related Art
In a prior art image surveillance system for security applications and so on for protecting persons and facilities from a suspicious person and an offender, a watcher always surveils many camera images visually for a long time with a very heavy load and with a low degree of efficiency. To solve this problem, there have been provided various ideas for extracting a scene in which a specific event occurs from an inputted image by carrying out image processing on the image, as disclosed in patent reference 3, and then providing information to attract the attention of the watcher for the watcher. To be more specific, there have been provided an intrusion surveillance system and so on for extracting a moving object, such as a person, from an inputted image by performing image processing on the image, and for issuing an alarm when this moving object intrudes into an area corresponding to an on-screen area which is specified in advance and then stays in the area for a specified time or more.
It seems that although such prior art systems can reoutput a list of detection results later after recording a detection result at a time of carrying out a detection in real time according to a query which is specified in advance, there are few systems which can change retrieval queries, such as a detection location and a staying time, after the detection, so as to retrieve a desired detection result again. In contrast, a prior art surveillance system disclosed in patent reference 1 keeps track of a moving object extracted from an inputted image and then records information about movements of the moving object. It therefore seems that the prior art surveillance system can change retrieval queries for the recorded time and space information after the detection so as to retrieve a desired record again.
Patent reference 2 discloses a method of dividing an image display screen into a plurality of partition regions, keeping tack of a moving object extracted from an image, and holding and displaying information about the traveling path of the moving object on a partition-region by-partition-region basis. It seems that the function of displaying the traveling path information operates at a high speed.
The surveillance system disclosed in patent reference 1 uses, as a method of holding information about the traveling path of the moving object, a method of holding, as an alpha map, all the positions of the moving object in image frames or a method of approximating the traveling path information with a spline function, and then holding the coefficients of the spline function. However, since the holding of the traveling path information using the former method is to substantially hold all images resulting from extraction of the moving object from the image frames through image processing and so on, the held information has a very large size. In a case of using the latter method, very complicated calculations are generally needed in order to represent the traveling path information about the traveling path of a moving object which is moving on the screen intricately with an equation, and therefore the implementation of the latter method is difficult in the case in which it is impossible to keep track of the moving object unless the processing load can be reduced, as in the case in which the inputted image is a live image and must be analyzed in real time. Also when retrieving a desired record, the surveillance system must determine whether each moving object matches with a certain retrieval query by performing a complicated higher-order polynomial arithmetic operation. Therefore, it may be difficult for the prior art surveillance system to retrieve a large amount of data at a high speed.
On the other hand, since the prior art surveillance system disclosed in patent reference 2 uses, as the holding method of holding the traveling path information about each moving object, a method of dividing an image display screen into a plurality of partition regions, and holding information about the traveling path of a moving object on a partition-region-by-partition-region basis, the prior art surveillance system can carry out information processing with a relatively light load. However, in patent reference 2, there is a reference made to holding of information about the staying time of the moving object in each partition region, while there is no reference made to any other information. Furthermore, there is a reference made to a method of displaying the information about the staying time, as well as the information about the staying time, while there is no reference made to retrieval based on a query.
[Patent Reference 1]
JP, 2004-64433,A (see paragraph numbers 0016 to 0020)
[Patent Reference 2]
Japanese patent No. 3601951 (see paragraph numbers 0020 to 0029)
[Patent Reference 3]
JP, 6-22318,A (see paragraph numbers 0006 to 0009)
A problem with the prior art image surveillance/retrieval systems constructed as mentioned above is that they cannot carry out any processing at a high speed and therefore cannot raise the efficiency of the image surveillance operation.